The provisions for the design of screwed connections in shear in AS/NZS 4600:1996 are mainly based on AISI - LRFD Specification (1996). The bearing force on the screw Vb is based on tilting and bearing mode of failure with an additional provision requiring the ‘nominal shear capacity’ of the screw shall not be less than 1.25 Vb. The applications of these rules are quite problematical in practice. Firstly, there is no definition of the ‘nominal shear capacity’. Secondly, the shear strength of screws is usually established by testing (because of case hardening) and the US and Australian rules for deriving design values from prototype testing are quire different. Thirdly, as the connected plates become thicker, shear failure of the screws becomes unavoidable and the rules become unworkable under some circumstances.

This paper seeks to explain these issues in details and proposes some changes to the associated design rules in line with the latest changes proposed in the new US Standard.